Lubricant



Patented Oct. 25, 1938 UNITED STATES LUBRICANT Lloyd P. Grobel, Schenectady, General Electric Company,

New York N. Y., assignor to a corporation of No Drawing. Application September 12, 1936 Serial No. 100,542 a 5 Claims.

The present invention relates broadly to lubricants or lubricating compositions. More particularly, it relates to and has as a main object-to improve the lubricating properties of hydrocarbon oil such, for example, as petroleum hydrocarbonlubricating oils. The desired result is attained by incorporating with a hydrocarbon oil a small amount of a member of the group con sisting of benzaldehyde, salicylic (or salicyl) aldehyde and benzoic acid.

For a consideration of what I.believe to be novel and my invention attention is directed to the following specification and the claims appended thereto.

It has been known heretofore that the lubricating power or capacity, that is, the film strength, of hydrocarbon oils such as petroleum lubricating oils may be improved by incorporating therein or commingling therewith certain modifying agents such, for instance, as free fatty acids, naturally occurring fatty oils, halogenated organic compounds (e. g., chlorinated esters of fatty acids, chloracetic acid, benzyl chloride, etc.) certain phosphorous compounds such astricresyl phosphate, various sulfur-containing com pounds, and so forth.

Although the addition of a fatty oil to a petroleum hydrocarbon lubricating oil produces a composition of somewhat improved film strength, such a lubricant is not always completely satisfactory in use since fatty oils tend to break down, especially at high temperatures with known disadvantages. Likewise, admixture of fatty acids with petroleum hydrocarbon oils is not always practically effective in producing desired results. The high molecular weightsaturated fatty acids show low film strengths, while those of low molecular weight, although they show higher film strengths, are corrosive to metal surfaces in the presence of moisture; and the unsaturated fatty acids tend to oxidize in use, forming undesirable gummy oxidation products. Other substances,

such as those hereinabove mentioned by way of example, may be efiective in producing lubricants of improved film strength, but many of such compositions, for example, those containing halogenated organic compounds, are objectionable in that they are corrosive to metal surfaces such as iron, steel and the like under certain conditions, for instance, in the presence of moist air. v

Inaccordance with the present invention, high film strength. lubricating oil compositions noncorrosive to metal surfaces are provided by intimately mixing with a hydrocarbon oil, such as a petroleum lubricating oil, a small amount, for example, from about 0.01 to 2.0 'per cent by weight, of an organic compound selected from the group consisting of benzaldehyde, salicylic aldehyde and benzoic acid.

To test the film strength of lubricants produced by this invention,.I have used a modified Almen extreme pressure lubricant testing machine. This device, which determines the pressure at which a lubricating" oil will break down to allow metal to metal contact, is fitted with V inch by inch bearings made from coldrolled steel rods. The bearings are split, each half carrying the total load, which is applied through a lever system by weights. The test shaft is made of ground unhardened steel drill rod and is run at 100 revolutions per minute. The two half bearings are assembled in proper position and suiiicient lubricant poured into the housing to submerge the bearing surfaces. The machine is started at light load and the load in; creased at second'intervals, by the addition of weights, at the rate of about 2,000 pounds per square inch bearing pressure. The weights are applied until seizure of the test bearing occurs or the capacity (45,300 pounds per square inch bearing pressure) of the machine is reached, or friction becomes sumciently great to cause-shear: ing of a brass pin in the driving couple. After the tests have beenrun, the test shafts are ex-' amined for corrosion. after remaining for several days in a closed vessel in. a water-saturated atmosphere.

' The results of the tests shown in Table I illustrate the greatly increased film strength possessed by lubricating oil compositions produced in accordance with this invention as compared with-the original mineral oil and with lubricants containing other addition agents:

' Table I Pounds per square inch pressure on rubbing surfaces when seizure of test bearing occurs Unmodified, that is, straigh petroleum hydrocarbon lubricating oil having a Saybolt Universal viscosity at 100.F. of

about 220 seconds 7,200 Same oil plus 1% by weight stearic acid 7,200 Same oil plus 1% by weight oleic acid 10,400 Same oil plus 1% by weight nitrotoluene 17,400 Same 011' plus 1% by weight benzyl alcohol 21,000 Same oil plus 1% by weight salicyclic aldehy i 38,000 Same oil plus 1% by weight benzalde- Same oil plus 1% by weight benzoic acid 39,500

. Examination of the test shafts for corrosion, after several days in a moist atmosphere, showed that none of the oil compositions containing the stated addition agents had a corrosive effect upon the metal surfaces. On the other hand, when samples composed of the same mineral oil and a small amount of,chlorinated compounds, for

tion may instance, 1% by weight chloracetic acid in one case and 1 by weight benzyl chloride in another, were prepared and tested, it was found that although such oil compositions had high film strength, that is, withstood a pressure on the rubbing surfaces of the order of about 40,000 pounds per square inch before seizure occurred, such lubricant had a corrosive effect upon the test shaft.

In practicing this invention only a small quantity of the addition agent is added to a hydrocarbon lubricant. Benzaldehyde, salicylic aldehyde or benzoic acid of a technical grade of purity may be used. The addition agent is well blended with the hydrocarbon oil by any suitable means, after which the composition is ready for use as a lubricant. i r

The invention is not limited to the preparation of oil compositions of improved film strength by admixture of the addition agent with a hydrocarbon oil of any particular viscosity, or of other particular physical or chemical properties, but is applicable to all hydrocarbon lubricants, including greases, irrespective of viscosity or classification. Lubricating compositionsof this invenbe employed at any and all points throughout any type of engine or machine structure, either in the form of an oil or a grease, and may be applied in the same manner as heretofore has been the common practice in the lubrication of machine structures. The compositions are especially adapted for use in lubricating rubbing surfaces operating at comparatively low speeds,

for example, in the lubrication of gears, pinions and the like.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A lubricating composition of high film strength comprising hydrocarbon oil and an organic compound selected from the group consisting of benzaldehyde, salicylic aldehyde and benzoic acid in an amount suflicient to increase the film strength of the said oil.

2. A lubricating composition of high film strength comprising petroleum hydrocarbon oil having incorporated therewith from 0.01 to 2.0 per cent by weight of an organic compound selected from the group consisting of benzaldehyde, salicylic aldehyde and benzoic acid.

3. A lubricating composition of high film strength consisting essentially of a petroleum hydrocarbon lubricating oil and benzaldehyde in an amount sufiicient to increase the film strength of the said oil.

4. A lubricating composition of high film strength consisting essentially of a petroleum hydrocarbon lubricating oil and salicylic aldehyde in an amount sufiicient to increase the film strength of the said oil.

5. A lubricating composition of high film strength consisting essentially of a petroleum hydrocarbon lubricating oil and benzoic acid in an amount suificient to increase the film strength of the said oil.

LLOYD P. GROBEL. 

